Estrada gave up seven runs and walked three in 3 1/3 innings in Tuesday night's loss to the Houston Astros. It was the second straight start that Estrada failed to make it past the fourth.
"He's had some back and hip things kind of in concert giving him a little trouble right now," A's manager Bob Melvin said. "He's had that in the past. We knew that 30-plus starts were probably not going to be realistic, and from time to time that this is something we were going to have to do with him. We knew all that going in."
Estrada signed a $4 million, one-year contract with Oakland in the offseason and has been second in Melvin's rotation. The A's are winless in his five starts.
Right-hander Chris Bassitt was recalled from Triple-A Las Vegas and is expected to take Estrada's place in the rotation.